What the Lone Star Step Down 24V to 12V Converter's current rating?
Per the manufacturer, Input: 27.5 Volts, Input: 5.6 Amps, Output: 14.06 Volts, Output 10 Amps.
Is the output adjustable? If so, what range?
No, the voltage is set at 12V and is not adjustable.
Is the Lone Star Step Down 24v to 12v TSOed?
Yes, it is.